This paper explores how insights from two-dimensional semantics can be brought to bear on debates surrounding (realist) metaethical naturalism. It defends two central claims. (1) A plausible principle of 2-D symmetry for normative terms provides us with reason to reject standard forms of synthetic metaethical naturalism. (2) Moore's Open Question Argument can be powerfully revived within the framework of 2-D semantics. I approach these issues by diagnosing how Attitudinal Semanticists' use of 2-D semantics--to account for moral objectivity--goes wrong. I argue that their "rigidification" strategy doesn't resolve, but merely pushes under the rug, the fundamental concerns that robust moral realists have with Attitudinal Semantics. These concerns re-emerge when we consider the intuitive symmetry between the primary and secondary intensions of normative terms. Attempts to restore symmetry via super-rigidity are subsequently shown to pose "Open Question" problems for (realist) metaethical naturalism more broadly.